Minke Whales (Balaenoptera acutorostrata)

Minke Whales on the Ledge: While minke whales remain poorly studied in the area, we do know that they are present year-round. Generally solitary, minke whales are thought to feed primarily on herring, although they will take a wide variety of fish as their prey. Because of their smaller size, they do not need as much food as the larger whales, and their distribution seem to be a bit less tied to explosive concentrations of prey on the Ledge. While there is no formal photo-identification effort for minke whales, resightings of certain distinctive individuals across many years indicate that at least some animals return to the Ledge on a regular basis. Size: 15-25 feet as adults Weight: approximately 5-8 tons as full grown adults Distinctive Characteristics: A sleek, small dolphin-like baleen whale; in the northern hemisphere there is a white strip across each flipper; dorsal fin is tall, sickle shaped, and near the middle of the back. Diet: Generally fish feeders in the northern hemisphere, krill feeders in the southern hemisphere. Because of their relatively small size, and lowered energetic needs, their diet is a wider variety of fish than the larger fin and humpback whales. At times, they may even take single larger fish rather than large quantities of smaller fish. Distribution: Minke whales are distributed world-wide, with three major distinct populations: the North Atlantic, North Pacific, and southern oceans. However, genetic work now indicates that the two hemispheres may contain different species of minke whales, as opposed to distinct populations of a single species. During summer minke whales are found from temperate waters all the way up to the ice pack. Their winter movements are poorly known; some may stay in temperate waters year-round, and there is recent acoustic evidence that some minke whales in the North Atlantic may move into tropical waters in the Caribbean during winter. Within their range, they are widely distributed, and are found over a more widespread area than their larger relatives. Life History: Very little is known of the life history of minke whales. Females are thought to give birth to one calf at a time once every 1-2 years. Mother-calf pairs are rarely observed, although in the past several years we have started to see what we think are independent calves (based on their size) with a probable mother staying in the general vicinity, but not with the youngster, with some frequency during September and October on Stellwagen Bank. Life span is unknown at this point. Social Organization: Minke whales are almost always seen by themselves, although they appear to aggregate (in concentrations which can number up fifty at a time) in productive food areas. While true side-by-side associations are unusual, these whales may work in small bands where individuals stay in each other's general vicinity. This appeared to be the case when two distinctive minke whales were seen on Stellwagen Bank throughout the summer of 1994; on days when one was seen, the other was also observed. However, this may have also been a coincidence of two whales following the same environmental cues. In the San Juan islands, where minke whales were studied for several years in the 1980's, individuals were found to be extremely site-specific and have feeding strategies which were specialized within the locality. How applicable these findings are to more open-ocean areas remains to be determined. Population Status: Minke whales are the most abundant whale in the world today, numbering well over 1,000,000 world wide. The highest population density is in the southern hemisphere, where up to 750,000 whales spend the summer feeding. Large populations also exist in the North Atlantic and North Pacific oceans. Minke whales are still commercially hunted by Norway, which kills up to 500 per year, and Japan (under a provision where research is done on the carcass, but the meat can still be sold on the open market), who takes up to 800 Antarctic Minke whales per year. The meat of these whales is considered a delicacy in Japan, where it sells for several hundred dollars per pound. Current threats to minke whales include expansion of the current hunt (which is being promoted by Japan, Norway, and Iceland), entanglements in fishing gear (since minke whales are not as strong as the larger species, they are more likely to become entangled and die), and degradation of their habitat from pollution. Other Sites: Link #1    Link #2    Link #3